Cancer is one of the leading causes of death in humans. Although a variety of drugs against neoplastic diseases have been developed and techniques are available such as surgery and radiation therapy, there is still a need for alternative and improved methods of treatment of neoplastic diseases.
Autoimmune diseases are associated with abnormal lymphoproliferation as a result of defects in the termination of lymphocyte activation and growth. Often, such diseases are associated with inflammation like rheumatoid arthritis, insulin dependent diabetes mellitus, multiple sclerosis, systemic lupus erythematosus and the like. The treatment of such diseases is focused on anti-inflammatory and immunosuppressive drugs which in numerous cases show severe side effects. Hence, there is a need for alternative drugs with a new mode of action showing less side effects.
Apoptosis is a term used to describe a series of cellular events which occur to bring about programmed cell death. There are various apoptotic pathways, some of which have been characterized, whereas others remain to be elucidated. If the balance between cell division and apoptosis is disturbed, life-threatening diseases including cancer, autoimmune disorders, neurodegenerative and cardiovascular diseases may occur.
In recent years it has become evident that programmed cell death (apoptosis) is as important to the health of a multicellular organism as cell division. By repeated cell division and differentiation throughout development or tissue repair, surplus or even harmful cells are generated. In order to maintain tissue homeostasis these cells have to be removed or killed. The delicate interplay between cell growth and apoptosis in an organism is mirrored in the complex molecular balance that determines whether an individual cell undergoes division, arrests in the cell cycle or commits to programmed cell death.
Dysregulation of cell proliferation, or lack of appropriate cell death, has wide ranging clinical implications. A number of diseases associated with such dysregulation involve hyperproliferation, inflammation, tissue remodeling and repair. Familiar indications in this category include cancers, restenosis, neointimal hyperplasia, angiogenesis, endometriosis, lymphoproliferative disorders, transplantation related pathologies (graft rejection), polyposis, loss of neural function in the case of tissue remodeling and the like. Such cells may lose the normal regulatory control of cell division, and may also fail to undergo appropriate cell death.
As apoptosis is inhibited or delayed in most types of proliferative, neoplastic diseases, induction of apoptosis is an option for treatment of cancer, especially in cancer types which show resistance to classic chemotherapy, radiation and immunotherapy (Apoptosis and Cancer Chemotherapy, Hickman and Dive, eds., Blackwell Publishing, 1999). Also in autoimmune and transplantation related diseases and pathologies compounds inducing apoptosis may be used to restore normal cell death processes and therefore can eradicate the symptoms and might cure the diseases. Further applications of compounds inducing apoptosis may be in restenosis, i.e. accumulation of vascular smooth muscle cells in the walls of arteries, and in persistent infections caused by a failure to eradicate bacteria- and virus-infected cells. Furthermore, apoptosis can be induced or re-established in epithelial cells, in endothelial cells, in muscle cells, and in others which have lost contact with extracellular matrix. These cells are potentially able to colonize other organs and therefore can develop into pathologies like neoplasias, endometriosis and the like.